Spark-induced breakdown spectroscopy (“SIBS”) is an atomic emission spectroscopic technique that can be used to detect and quantify the elemental content of an analyte. In operation, a powerful electric spark discharge between two electrodes creates a small volume of a high-temperature plasma. An analyte, which may be aerosolized, is quickly vaporized and/or atomized by the plasma. High-energy electrons from the electric spark excite the analyte atoms to one or more excited electronic states. As an element relaxes back toward the ground state, it emits a characteristic atomic emission spectrum which is detected by a spectrometer and recorded. Based on the signature emission spectrum, the elemental content of the analyte can be determined. A representative SIBS apparatus is disclosed in U.S. Pat. No. 6,034,768, the entire teachings of which are incorporated herein by reference.
Such systems can be used for real-time detection of elements in an analyte, which may be used to detect the presence of hazardous airborne heavy metals, such as lead or chromium, or other chemicals, such as chemical or biological weapons. Other applications of the technology include process control, emission compliance, and industrial hygiene.
While SIBS is a sensitive technique for elemental detection, it is not without its drawbacks. Generating a spark requires the use of two electrodes positioned at an appropriate distance. Over time, the electrodes wear down and become smaller in length, which causes two problems. As the electrodes degrade, debris from the electrodes accumulates within the housing where the spark is generated. This debris can coat the optical equipment and reduce sensitivity of the apparatus, thereby requiring periodic cleaning. In addition, as the electrodes erode, the location of the spark may shift. In precision analytical equipment, even modest adjustments in the location of the spark can impact the sensitivity of the measurement.
Accordingly, there is a need for an improved SIBS apparatus that can be used to determine the elemental content of an analyte, particularly an aerosolized analyte, that substantially prevents debris from fouling the optical equipment and at least partially stabilizes the spark location.